硼钢板热冲压成形过程接触热阻研究

Research on thermal contact resistance for boron steel sheet in hot stamping process

高强度钢热成形中,板料的冷却路径直接影响成形后零件的力学性能,可靠的接触热阻能提高热成形温度场模拟计算结果的准确性。为了研究热冲压成形过程中板料与模具界面间的接触热阻,以WH1300HF热成形用无涂层硼钢板为研究对象,在小型实验伺服压力机上进行了硼钢板的热冲压平模实验,得到了不同压强下板料淬火冷却曲线及模具温度冷却曲线,并通过顺序函数法计算出板料和模具接触界面的热流密度及接触热阻。研究结果表明,板料与模具间界面的热流密度峰值随压强增加而增加,接触热阻稳定值随压强增加而减小。根据能量守能定律,计算出热冲压硼钢板马氏体相变潜热及平模淬火实验中马氏体相变分数。

The cooling path of blank directly affects mechanical properties of formed parts in the hot stamping process of high strength steel,and reliable thermal contact resistance can improve the accuracy of simulation results of temperature fields in the hot stamping process. In order to research the thermal contact resistance of interface between blank and die in the hot stamping process,for boron steel sheet WH1300 HF without coating for hot stamping,a flat die experiment of hot stamping for boron steel sheet was performed on a small experimental servo press,and the cooling curves of blank quenching and die temperature under different pressures were obtained. Furthermore,the heat flux density and the thermal contact resistance of interface between blank and die were estimated by sequential function method. The results show that the peak values of heat flux density of interface between blank and die increase with the increasing of pressure,and the stable values of thermal contact resistance decreases with the increasing of pressure. Thus,according to the law of energy conservation,the latent heat of martensitic phase transformation in the hot stamping process for boron steel sheet and the martensitic fraction in the flat die quenching experiment were calculated.